The present application claims priority under 35 USC 119 to Japanese Patent Application No. 2001-239982 filed on Aug. 7, 2001 the entire contents thereof is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a shock absorber for a two-wheeled vehicle for effectively protecting an occupant against a frontal crash of a two-wheeled vehicle.
2. Description of the Background Art
A shock absorber is used in an automotive vehicle for protecting occupants in case of a collision. For example, shock absorbers are provided inside of pillar garnishes for protecting the heads of the occupants and inside of the door trims for protecting the backs or the chests of the occupants and the like in case of a side collision. A shock absorber with resin ribs can be manufactured at relatively low cost and has been in heavy usage as set forth in JP-A-8-164810, JP 2978083, etc.
However, with regard to two-wheeled vehicles the absorption of energy in case of a collision has not been examined so far.
The shock absorber for a two-wheeled vehicle is required to absorb a much larger energy in comparison with that for an automotive vehicle. For example, in the case of an automotive vehicle, kinetic energy to be absorbed Ek=xc2xd mv2 is 102.1 [J], which is determined based on energy generated when a dummy head of 4.54 kg in mass clashes at the speed of 15 mile/hr. (=6.71 m/s), while in the case of a two-wheeled vehicle, kinetic energy to be absorbed Ek is 9646 [J], where the vehicle mass is 100 kg, and the traveling velocity is 50 km/hr. (=13.89 m/s), which means that incommensurably large energy absorption must be realized.
Assuming that a resin rib for an automotive vehicle is used, since the height of the rib is in the order of 60 mm at most, a considerably large area is required on the two-wheeled vehicle when it, having the same absorption stroke, is applied thereto, which is actually impossible. Because the shock absorber is to be mounted at the front end of the two-wheeled vehicle, it was impossible to enlarge the front area thereof. On the other hand, assuming that a method of increasing the height of resin rib is employed, the rib may be ever-increasingly thicker because it is necessary to provide a draft angle for manufacturing reasons, thereby resulting in a disadvantage in that a generated load increases.
In order to solve the aforementioned problems, it is an object of the present invention to provide a shock absorber for a two-wheeled vehicle that effectively absorbs a large energy generated in case of a collision and that may be easily mounted on a two-wheeled vehicle.
In order to achieve the aforementioned object the present invention is directed to a shock absorber for a two-wheeled vehicle that includes a tabular top board, and a lattice body including a plurality of plate ribs being reduced in thickness from the proximal ends toward the distal ends and molded integrally with the top board so as to project upwardly thereon and intersectionally with respect to each other. Shock absorbing members of synthetic resin having projecting rib portions formed at outermost lattice openings of the lattice body by extending some of the plate ribs that are disposed intersectionally with respect to each other outwardly and having the top board overhanging outwardly of the outermost lattice openings of the lattice body are disposed in such a manner that the direction of the plate ribs extending from the proximal ends toward the distal ends is oriented along the fore-and-aft direction of the two-wheeled vehicle, stacked in such a manner that the distal ends of the plate ribs abut against the top board of the shock absorbing member to be disposed adjacent thereof, and then mounted at the front end of the two-wheeled vehicle.
The shock absorber for a two-wheeled vehicle according to the present invention includes the lattice opening at the center of the lattice body that is made larger than the lattice openings formed on the portion other than the center.
According to the present invention, when the lattice body is disposed in such a manner that the direction of the plate ribs extending from the proximal end towards the distal end is oriented along the fore-and-aft direction of the two-wheeled vehicle, stacked in such a manner that the distal ends of the plate ribs abut against the top board of the shock absorbing member to be disposed adjacent thereof, and then mounted at the front end of the two-wheeled vehicle, stacking of lattice bodies contributes to secure a large shock absorbing stroke for a frontal collision of the two-wheel vehicle, thereby being able to absorb a large impact as desired. In addition, since the shock absorbing members are stacked, the height of the plate rib in the lattice body, which constitutes each tier, may be reduced to a value in the order of 60 mm, so that the proximal end of the rib is prevented from being too thick even when a draft angle is provided. Thus, disadvantages such as an increase in the generated load may not arise.
Further, when shock absorbing members of synthetic resin having projecting rib portions are formed at outermost lattice openings of the lattice body by extending at least one of the plate ribs that are disposed intersectionally with respect to each other outwardly and when the top board overhanging outwardly of the outermost lattice openings of the lattice body is used, a stack of individual shock absorbing members may be prevented from being off balance when being subjected to an impact load, and the plate ribs constituting the shock absorbing member being crushed while being buckled and deformed evenly as a whole, thereby absorbing the impact load effectively.
Furthermore, when the shock absorbing members including the lattice body and the top board molded integrally with each other are stacked, when each of stacked shock absorbing members is subjected to a impact load, the top board receives the load as a whole in a first position, and then the load is transmitted to each plate rib, and then the plate ribs are crushed continuously to absorb the impact load effectively.
According to the present invention, when the lattice opening at the center of the lattice body is determined to be larger than the lattice opening located on the portion other than the center, the strength of the shock absorber formed by stacking the shock absorbing members is low at the portion near the central axis, and thus it is crushed stably when being subjected to a impact load.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.